1. Technical Field
The present disclosure relates to an iron-based sintered alloy to be suitably used as a die material and a cutter blade material for a pelletizer of a resin extruder in pairs, and a method for producing the same.
2. Description of the Related Art
Since a cutter blade or the like for a pelletizer of a resin extruder is severely worn under a corrosive environment, excellent corrosion resistance and wear resistance are required. Also, a tool material to be used in the cutter blade and the like for a pelletizer of a resin extruder desirably has not only excellent corrosion resistance and wear resistance but also machinability for processing the material into the cutter blade or the like. To such a request, for example, JP-A-H11-92870 proposes a material which is machinable, has a predetermined level of hardness and excellent wear resistance, and is excellent in corrosion resistance, obtainable by dispersing appropriate amounts of carbides in high strength stainless steel. That is, there is proposed a highly corrosion-resistant carbide-dispersed material in which carbides of Ti and Mo are dispersed in a matrix, wherein the carbide-dispersed material contains, in terms of weight ratio, Ti; 18.3 to 24%, Mo; 2.8 to 6.6%, C; 4.7 to 7% as the carbides and contains Cr; 7.5 to 10%, Ni; 4.5 to 6.5%, Co; 1.5 to 4.5%, and 0.6 to 1% of one or more of Al, Ti, and Nb as the matrix, the balance being Fe and unavoidable impurities.
Moreover, JP-A-2000-256799 proposes a highly corrosion-resistant carbide-dispersed material in which carbides of Ti and Mo are dispersed in a matrix, wherein the carbide-dispersed material contains, in terms of weight ratio, Ti; 18.3 to 24%, Mo; 2.8 to 6.6%, C; 4.7 to 7% as the carbides and contains Cr; 7.5 to 10%, Ni; 4.5 to 6.5%, Cu; 1 to 4.5%, Co; 0 to 4.5%, and 0.6 to 1% of one or more of Al, Ti, and Nb as the matrix, the balance being Fe and unavoidable impurities. According to the example, the highly corrosion-resistant carbide-dispersed material has a hardness of 46.0 to 49.8 HRC after sintering, is machinable, and has a hardness of 58.0 to 63.5 HRC and a bending strength of 126 to 155 kgf/mm2 after an aging treatment.
However, resin materials to be used in a resin extruder are various materials and application ranges thereof have been extended, so that the tool material to be used for the cutter blade and the like for a pelletizer is required to have higher corrosion resistance, wear resistance, machinability, or mechanical strength. The highly corrosion-resistant carbide-dispersed materials proposed in JP-A-H11-92870 and JP-A-2000-256799 have a problem that they cannot always cope with such requirements sufficiently.